The present invention relates to systems for optical inspection. More particularly, this invention relates to camera boxes used in systems for optically inspecting cylindrical surfaces such as the cylindrical surfaces of cigarettes.
Systems for optically inspecting cylindrical surfaces are described by the above-incorporated, commonly-assigned United States patent application Ser. No. 07/884,746, filed May 15, 1992. That application describes optical inspection systems that operate by first inspecting at least 180.degree. of the circumference of a first side, and then inspecting at least 180.degree. of the circumference of the other side. The inspection systems illuminate more than 180.degree. of the circumference of the object by utilizing two, angularly spaced, light sources. Images of the illuminated object are then formed (using camera boxes and computer processors), which images are analyzed using various techniques to make possible the detection of very small defects, as well as to compensate for possible nonuniform illumination of the objects in the circumferential direction.
A possible disadvantage of the camera boxes of the above-incorporated patent application is the large size required, due to the fact that the camera boxes contain a conventional video camera, two lights sources, and a series of apertures and reflectors which are used to form the image. A further possible disadvantage of the camera boxes is the system installation limitation due to the straight in-line nature of the conventional video camera. These disadvantages may result in requiring extra intermediate drums to provide adequate installation space for the camera boxes, in addition to the overall increased space requirements of the inspection system itself.
Another possible disadvantage of the camera boxes of the above-incorporated application is the fact that the camera boxes are not sealed units. The aperture design of the camera boxes is such that it may permit particle contamination of the optics, and the camera itself, to occur. Such contamination may occur due to the nature of the manufacturing operation (e.g., production rates approaching 10,000 cigarettes a minute may cause loose tobacco fibers and ,other contaminants to be introduced into the manufacturing environment).
A further possible disadvantage of the camera boxes of the above-incorporated application is the ability to sufficiently illuminate the object during inspection. The inspection system may utilize additional image processing techniques to compensate for possible nonuniform illumination of the objects in the circumferential direction and the elimination of shadows, but such additional image processing may limit the speed at which the inspection system can process images.
The above-incorporated patent application describes that it may be desirable to make the inspection images fall on a particular portion of the camera screen. Such placement of the images enables the system to easily combine the signal of the image captured from the first camera with the signal of the image from the second camera (e.g., through the use of a simple multiplexer). The camera boxes of the above-incorporated patent application accomplish image placement by varying the locations and angles of the apertures and mirrors of the image capturing system. Unfortunately, this may require that each of the two cameras of the inspection system be unique, for each must have different locations and angles for its apertures and mirrors.
It would therefore be desirable to provide camera boxes that have a separate housing for the lens arrangement, with the separate housing having the capability to interface with a video camera at different angles in addition to straight in-line.
It would also be desirable to provide camera boxes that can are sealed to prevent contamination of the lens arrangement without interfering with the image capturing process.
It would further be desirable to provide camera boxes that provide still more illumination of the objects during inspection to further reduce the image processing requirements of the inspection system.
It would be still further desirable to provide camera boxes which are adjustable, such that the position of the received image can be varied within the camera screen without affecting the lens arrangement.